1. Field of the Invention
The present invention relates to carriage mounted press-loading mechanism for inserting lay-ups of sheet material between the spaced platens of a multiplaten press.
2. Prior Art
Sheet-processing presses are known having several horizontally extending, vertically spaced platens for receiving a pack or lay-up of sheet material in each space between adjacent platens. An example of such a press is a plywood bonding press having heated platens for pressing lay-ups of glued veneer sheets to set the glue and form uniform plywood sheets.
Previously, separate veneer sheet lay-ups have been inserted consecutively in the spaces between the platens of such a multiplaten press, either automatically by a mechanical press loader or manually; or a full set of lay-ups has been inserted into such a press simultaneously by a mechanical press loader. Simultaneous loading is desirable to reduce loading time, assuring maximum use of expensive multiplaten presses, and also to ensure uniform processing of the lay-ups. In the case of a plywood bonding press having a large number of heated platens, such as twenty or more, consecutive loading may result in the adhesive of the first loaded lay-up setting or curing even before the press is completely loaded.
Known mechanical press loaders have several horizontally extending, vertically spaced shelves for supporting sheet material lay-ups in edgewise registration with the spaces between the platens of an open press. In the loaders of Pierce U.S. Pat. No. 2,663,434 and British Pat. No. 433,778, vertical pusher bars move through slots in the shelves for simultaneously sliding all of the lay-ups off the shelves and into the press. In the loader of Bowen et al. U.S. Pat. No. 2,438,896, separate pushers are provided for each shelf, but all of the pushers are moved together for simultaneously sliding the lay-ups off the shelves and into the press. In the loaders of the Skoog U.S. Pat. No. 2,376,457 and Siempelkamp U.S. Pat. No. 2,728,468, the lay-up-supporting shelves themselves are inserted into the press. Each shelf of the Skoog loader has an associated horizontal pusher bar that slides its lay-up off the shelf onto a press platen as the shelf is retracted from the press whereas the Siempelkamp device has stop members mounted on the press for holding the lay-ups in the press as the shelves are retracted.